Modern sporting rifles as well as military rifles and carbines must be robust for reliable operation, and lightweight to permit carry without excessive fatigue. Significant reduction in rifle weight has been previously achieved by replacing wood with polymer material for components such as the shoulder stock and fore stock. Such designs have been successful because the use of polymer material for these elements does not compromise the robustness or reliable operation of modern firearms.
However, components such as the receiver and its associated assemblies such as the bolt carrier and barrel still account for a significant portion of the weight of a firearm, as it has not been thought feasible to substitute polymer for such parts which experience heat, pressure and wear from reciprocating motion. To meet the harsh requirements of operation many receiver designs are machined from a solid aluminum billet, and thus represent, in addition to significant weight, a significant production cost, as the machining is complex and constrained by tight tolerance requirements. There is clearly a need to further reduce rifle weight and simplify production without compromising the performance of the modern combat or sporting rifle.